# US 2022/0045787 A1 · Optical network using optical amplifier in gain saturation region

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- Number: US 2022/0045787 A1
- Document ID: US20220045787A1
- Status: Published application
- Kind: A1
- Application number: 17/394,735
- Filed: 2021-08-05
- Published: 2022-02-10
- Earliest claimed: 2020-08-06
- Assignees: Flectronics and Telecommunications Research Institute
- Applicants: Flectronics and Telecommunications Research Institute
- Inventors: Han Hyub LEE; Hwan Seok CHUNG
- Web page: https://patentgrep.com/patent/US20220045787A1

## CPC

- H01S 5/50: Amplifier structures not provided for in groups H01S5/02 - H01S5/30
- H04B 10/50: Transmitters
- H01S 5/0683: by monitoring the optical output parameters
- H04B 10/07955: {Monitoring or measuring power}
- H04B 10/2914: {using lumped semiconductor optical amplifiers [SOA]}
- H04B 10/69: Electrical arrangements in the receiver
- H04L 1/0042: {Encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit distortions, jitter, or to improve signal shape (H04L1/0067 takes precedence)}
- H01S 5/0617: {using memorised or pre-programmed laser characteristics}
- H01S 2301/02: ASE (amplified spontaneous emission), noise; Reduction thereof
- H04L 1/0061: {Error detection codes}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

An optical network using an optical amplifier in a gain saturation region includes an optical transmission apparatus. The optical transmission apparatus includes an optical transmitter configured to output an optical signal, a semiconductor optical amplifier (SOA) configured to amplify the optical signal outputted through the optical transmitter, and a controller configured to control the SOA to operate in a gain saturation region or a linear gain region depending on whether a forward error correction (FEC) function is used in the optical network.

## Claims

### Claim 1

An optical network comprising:
an optical transmission apparatus,
wherein the optical transmission apparatus comprises:
an optical transmitter configured to output an optical signal;
a semiconductor optical amplifier (SOA) configured to amplify the optical signal outputted through the optical transmitter; and
a controller configured to control the SOA to operate in a gain saturation region or a linear gain region depending on whether a forward error correction (FEC) function is used in the optical network.

### Claim 2 (depends on 1)

The optical network of claim 1, wherein the controller is configured to:
control the SOA to operate in the gain saturation region when the FEC function is used in the optical network, and
control the SOA to operate in the linear gain region when the FEC function is not used in the optical network.

### Claim 3 (depends on 1)

The optical network of claim 1, wherein:
the controller is configured to control an optical output of the optical transmitter and an operating condition of the SOA based on gain saturation of the SOA, and
the gain saturation of the SOA is determined based on amplified spontaneous emission (ASE) noise of the SOA.

### Claim 4

An optical network comprising:
an optical transmission apparatus,
wherein the optical transmission apparatus comprises:
an optical transmitter configured to output an optical signal;
an SOA configured to amplify the optical signal outputted through the optical transmitter; and
a controller configured to control an optical output of the optical transmitter and an operating condition of the SOA based on gain saturation of the SOA, and
the gain saturation of the SOA is determined based on ASE noise of the SOA.

### Claim 5 (depends on 4)

The optical network of claim 4, wherein the controller comprises:
a first optical power meter configured to measure an optical power of a first optical signal outputted by distributing, through an optical distributer, an optical signal amplified through the SOA to include the ASE noise;
an optical filter configured to filter a second optical signal other than the first optical signal outputted through the optical distributer;
a second optical power meter configured to measure an optical power of the second optical signal from which the ASE noise is filtered by the optical filter; and
a processor configured to determine the gain saturation of the SOA using the first optical power measured through the first optical power meter and the second optical power measured through the second 1 optical power meter.

### Claim 6 (depends on 5)

The optical network of claim 5, wherein the gain saturation of the SOA is determined using a difference between the first optical power and the second optical power.

### Claim 7 (depends on 4)

The optical network of claim 4, the controller is configured to increase the optical output of the optical transmitter or decrease an operating current of the SOA when the determined gain saturation of the SOA has a value greater than or equal to a preset value.

### Claim 8 (depends on 4)

The optical network of claim 4, the controller is configured to decrease the optical output of the optical transmitter or increase an operating current of the SOA when the determined gain saturation of the SOA has a value less than a preset value.

### Claim 9 (depends on 4)

The optical network of claim 4, wherein the controller is configured to control the optical output of the optical transmitter and the operating condition of the SOA according to the determined gain saturation of the SOA using a feedback loop or a look-up table.

### Claim 10

An optical transmission method in an optical network, the method comprising:
distributing an optical signal including ASE noise outputted by an optical transmitter and amplified through an SOA using a first optical distributer;
distributing a partial output of the first optical distributer using a second optical distributer;
measuring a first optical power of a first optical signal outputted through the second optical distributer to include the ASE noise;
filtering a second optical signal outputted through the second optical distributer using an optical filter;
measuring a second optical power of the second optical signal from which the ASE noise is filtered by the optical filter; and
determining gain saturation of the SOA using the first optical power and the second optical power.

### Claim 11 (depends on 10)

The method of claim 10, wherein the gain saturation of the SOA is determined using a difference between the first optical power and the second optical power.

### Claim 12 (depends on 10)

The method of claim 10, further comprising:
controlling an optical output of the optical transmitter and an operating condition of the SOA based on the determined gain saturation of the SOA.

### Claim 13 (depends on 12)

The method of claim 12, wherein the controlling comprises increasing the optical output of the optical transmitter or decreasing an operating current of the SOA when the determined gain saturation of the SOA has a value greater than or equal to a preset value.

### Claim 14 (depends on 12)

The method of claim 12, wherein the controlling comprises decreasing the optical output of the optical transmitter or increasing an operating current of the SOA when the determined gain saturation of the SOA has a value less than a preset value.

### Claim 15 (depends on 12)

The method of claim 12, wherein the controlling comprises controlling the optical output of the optical transmitter and the operating condition of the SOA according to the determined gain saturation of the SOA using a feedback loop or a look-up table.